Solve for $x$ and $y$ using substitution. ${-4x-5y = -9}$ ${x = -2y+3}$
Explanation: Since $x$ has already been solved for, substitute $-2y+3$ for $x$ in the first equation. ${-4}{(-2y+3)}{- 5y = -9}$ Simplify and solve for $y$ $8y-12 - 5y = -9$ $3y-12 = -9$ $3y-12{+12} = -9{+12}$ $3y = 3$ $\dfrac{3y}{{3}} = \dfrac{3}{{3}}$ ${y = 1}$ Now that you know ${y = 1}$ , plug it back into $\thinspace {x = -2y+3}\thinspace$ to find $x$ ${x = -2}{(1)}{ + 3}$ $x = -2 + 3$ ${x = 1}$ You can also plug ${y = 1}$ into $\thinspace {-4x-5y = -9}\thinspace$ and get the same answer for $x$ : ${-4x - 5}{(1)}{= -9}$ ${x = 1}$